The obesity pandemic that affects all segments of the population threatens to dramatically increase the prevalence of cardiovascular disease, including the pregnancy syndrome preeclampsia (PE). Pre-pregnancy obesity increases the risk of PE, including early or severe PE, 2 to 3 fold. With the high prevalence of obesity in reproductive age women, this results in an attributable risk of PE from overweight and obesity of 25 to 50%. Furthermore, the metabolic milieu believed to impair vascular endothelial function in the obese (insulin resistance, chronic inflammation, dyslipidemia, increased asymmetric dimethylarginine (ADMA;an endogenous inhibitor of nitric oxide synthase) is also the milieu we suggest interacts with poor placentation to promote the endothelial dysfunction of PE. Collectively, our data point to maternal pregravid obesity as the major, modifiable, risk contributing to PE. In the next 5 years, we propose to focus on the mechanisms by which obesity increases the risk of PE. Novel approaches will be used to identify, and then determine the functional significance of PE-associated changes in cytotrophoblast gene expression as these cells differentiate along the invasive pathway (Project I). In this context, we find that molecules involved in lipid synthesis or lipid metabolism are among the most highly modulated. We will also study obese and lean women with and without PE (Projects II-IV) and obese rodent models (Projects IV and V). Project II examines components of obesity (metabolic, inflammatory and life style) for association with preeclampsia and whether these converge to increase ADMA. Project III tests the concept that the number and angiogenesis-related activities of circulating, maternal endothelial progenitor cells (EPCs) are suppressed in women with PE compared to normal pregnancy, particularly in obese women with PE. Project IV is designed to explore how myeloperoxidase and related inflammatory/oxidative pathways intersect with dyslipidemia to increase the risk of PE in obese women. Projects II-IV with Core B propose to directly examine the role of ADMA and nitric oxide with a 3 week randomized, controlled trial of L-arginine supplementation in a cohort of obese women during early 2nd trimester, with assessment of vascular function and related intermediate endpoints. Project V will compliment Project II by directly investigating the role of obesity and ADMA on vascular function, EPC number and function, angiogenesis and trophoblast function. These coordinated studies will begin to elucidate the mechanisms by which pre-pregnancy obesity increases the risk of PE, and the biologic differences between obese women who develop PE and obese women who do not develop PE. With our preclinical and clinical approaches, our track record, and the many interactions among the five projects, we expect the next funding period to result in the translation of fundamental knowledge to clinical practice.